\begin{problem}{Electronic Scarecrows}{scarecrows.in}{scarecrows.out}{2 seconds}{}{}
 
In the future, farmers won't have to rely on primitive scarecrows to 
keep the birds away from their crops. A new revolutionary invention, 
an ``electronic scarecrow'', will make sure the birds stay out of 
the farmers' fields forever. 

If you have three electronic scarecrows located on a field so that they 
form a triangle, a bird won't be able to fly inside this area because it 
will get zapped by a laser beam coming out from the scarecrows. Of course, 
if you have more scarecrows, the whole area that is surrounded by these 
scarecrows becomes protected (this area is known as the convex hull). Consider 
the picture below: 

\begin{center}
\includegraphics[width=5cm]{pics/scarecrows.eps}
\end{center}

The black dots represents electronic scarecrows and the area shaded gray is 
the part of the field that is inaccessible to the birds. 

This sounds great, but there are two drawbacks. First, the scarecrows are 
of course very expensive, so a farmer can't afford very many of them. 
Second, they are quite heavy and need firm soil to stand on, 
and must also be in range of a power outlet. This severely limits 
the number of locations the farmer can place such scarecrows. 

Given the coordinates of possible locations for the scarecrows and 
the maximum number of scarecrows the farmer can afford to buy, 
calculate the largest area that can be guarded by these scarecrows. 
The farmer's field is a rectangular area, and all locations given 
will be inside this area. 

\InputFile

The first line of the input contains the 
maximum number of scarecrows the farmer can afford to buy $n$ 
($3\le n\le 40$) and
the number of possible locations for the scarecrows $m$
($3\le m\le 40$).
The next $n$ lines contains two numbers $x_i$ $y_i$ each --- the
coordiantes of possible locations for the scarecrows. Coordinates
are in range from 0 to $1\,000$. No location will appear more than once. 

\OutputFile


Output the largest area the scarecrows can cover. 
You may safely assume that it will always be possible 
to put the scarecrows so they will cover an area strictly 
greater than 0. A solution will be judged correct if the 
absolute or relative error is within 1e-9.
 
\Example

\begin{example}
\exmp{
4 7
2 2
1 5
6 1
5 5
3 7
7 6
9 4
}{
24
}%
\end{example}

\end{problem}